1. Field of Invention
The present invention relates to a projection lens manufacturing apparatus, a projection lens manufacturing method, a projection lens manufactured by the projection lens manufacturing method and a projector having the projection lens.
2. Description of Related Art
A related art projector having a plurality of liquid crystal panels for respectively modulating a plurality of color lights in accordance with image information, a cross dichroic prism for combining the color lights modulated by the respective liquid crystal panels, and a projection lens for projecting the light beam combined by the prism in an enlarged manner to form a projection image has been used.
As a projection lens used for such a projector, a compound lens composed of a combination of a plurality of lenses including a converging lens and a diverging lens is used in order to minimize deterioration in resolution and spherical and color aberration. However, in order to have the lenses function correctly and obtain a high-quality projected image, the position of the optical axis (core) of respective lenses of the projection lens should be adjusted with high accuracy.
In the related art, after accurately processing the profile of the plurality of lenses and a lens-holding barrel that holds the lenses, a trial-and-error process was conducted for producing a high-quality projection lens, where a part of the components is exchanged until the optical axis is aligned by observing the projected image. However, since the variation of profile accuracy of the components dominates over the accuracy of optical axis alignment in such arrangement, the optical axis cannot be accurately adjusted and troublesome work is necessary for the trial-and-error production process.
Accordingly, an arrangement for a projection lens has been proposed, where holes for adjusting the lens position are provided on a lens-holding barrel on three locations at a regular interval on a plane orthogonal with the illuminating optical axis of the optical path formed inside the lens-holding barrel and a pin-member such as a screw directed from the outside to the center of the barrel is attached to the three position-adjusting holes. In such projection lens, the three pins are advanced and retracted to bias the lens to be adjusted so that the position of the lens is adjusted within the plane orthogonal with the illuminating optical axis.
Another arrangement has been proposed where the lens to be adjusted is clamped at a predetermined position and the lens-holding barrel accommodating the lens is moved to adjust the position of the lens. See Japanese Patent Laid-Open Publication No. Hei 8-334664.
Still another arrangement has been proposed where the lens is fixed by caulking inside the lens-holding barrel provided with a distortion absorber and, subsequently, the lens position is adjusted by moving the lens. See Japanese Patent Laid-Open Publication No. 2002-189159. The distortion generated by adjusting the lens is absorbed by the distortion absorber, whish is removed by beating.
In a further alternative related art arrangement, a lens-holding barrel for holding the lens is constructed of a first lens-holding barrel and a second lens-holding barrel provided on the outside of the first lens-holding barrel, and a lens-holding spring is disposed between the first lens-holding barrel and the second lens-holding barrel. The lens-holding spring is compressed by a screw provided on the second lens-holding barrel to adjust the first lens-holding barrel by moving in a direction orthogonal to the optical axis. See Japanese Patent Laid-Open Publication No. 2002-40308. In this arrangement, a holding ring is provided on the front end of the first lens-holding barrel and the first lens-holding barrel is sandwiched and fixed between the holding ring and the second lens-holding barrel.
However, in the related art method for adjusting the lens position where a pin is provided on the projection lens as a product itself, large number of components are required for constructing the projection lens, which results in high production cost and increase in size and weight of the projection lens.
In the related art arrangement where the in-plane position of the lens is adjusted to have directions, when one of the pins are advanced or retracted, the other two pins also have to be advanced or retracted, which makes it difficult to know how far the two pins have to be moved, in other words, to recognize the relationship between the advancement and retraction of the pins and the direction for the lens to be moved, thereby requiring complicated work for adjusting the optical axis. At this time, since the respective pins advance and retract in different directions, the opening area of the position-adjusting hole has to be set wide to some extent in accordance with the lens to be adjusted, which can result in deterioration in the quality of the projected image on account of light leakage through the opening.
According to the method disclosed in JP-8-334664, since a lens fixed to the lens-holding barrel is moved in accordance with the movement of the lens-holding barrel, the center of the fixed lens relative to adjustment light source is shifted. Accordingly, it can be difficult to align the optical axis of the fixed lens with the optical axis of the lens to be adjusted, thus being unable to adjust the optical axis position of the lens with high accuracy.
According to the method disclosed in JP-2002-189159, since the distortion absorber has to be provided on the lens-holding barrel, the size of the lens-holding barrel and, as a result, the projection lens having the lens-holding barrel is increased. Further, since the distortion generated on the distortion absorber is removed by heating, the lens cannot be made of plastics with low-heat resistance. Further, since the lens position fixed on the lens-holding barrel is adjusted against the holding force of the lens-holding barrel, fine-adjustment, i.e. adjusting the lens position with high-accuracy may become difficult.
According to the method disclosed in JP-2002-40308, since a position adjusting mechanism composed of lens-holding spring and screw is provided on the projection lens, the number of components of the projection lens is increased and the structure of the projection lens becomes complicated. Further, in order to provide such position-adjusting mechanism having such lens-holding spring and screw on the projection lens, the projection lens must be provided with two lens-holding barrels, i.e. the first lens-holding barrel and the second lens-holding barrel, which requires a holding ring provided on the front side of the first lens-holding barrel for fixing the first lens-holding barrel to the second lens-holding barrel, so that the size of the projection lens is increased in the optical axis direction.
The present invention provides a projection lens manufacturing apparatus and a projection lens manufacturing method capable of reducing the number of components to enable reduction in cost, size and weight of a projection lens, of easily adjusting the position of optical axis of a plurality of lens of the projection lens with high accuracy to obtain a high-quality image projection, and of easily manufacturing a projection lens without limiting the material to be used for the lens, a projection lens manufactured by the projection lens manufacturing method, and a projector having the projection lens.
A projection lens manufacturing apparatus according to an aspect of the present invention is for manufacturing a projection lens including a lens-holding barrel with a predetermined optical path being set inside thereof and a plurality of lenses sequentially arranged on an illuminating optical axis of the optical path, a pair of position-adjusting holes formed respectively on two axes orthogonal to each other to adjust the position of at least one of the plurality of lenses on a plane orthogonal to the illuminating optical axis along the two axes, the apparatus having: a light source that irradiates an adjustment light beam; a projection lens holding mechanism that holds a lens to be manufactured at a lens-holding position for adjusting the position of the lens to be adjusted on the illuminating optical axis; an image light irradiation mechanism that forms an image light including a predetermined test pattern in accordance with the light beam irradiated by the light source and introduces the image light into the projection lens located at the lens-adjusting position; two lens position adjusters that respectively adjust the position of the lens to be adjusted along the two axes through the lens position-adjusting holes while detecting the image light projected by the projection lens into which the image light is introduced; and a bonding mechanism that bonds the position-adjusted lens to the lens-holding barrel.
The plurality of lenses include at least two groups of lenses, and the number of the groups, and the shape, the size and the function of the lens are not restricted. The lens to be adjusted is one or more lenses to be adjusted, where a lens that most influences on the quality of projected image is selected as the lens to be adjusted. The number of the lens position adjuster may be set in any manner according to the number of the lens to be adjusted.
The lens-holding barrel of the projection lens to be manufactured may have a collar to be attached to an end of an optical system of the projector in which the projection lens is installed.
In the above arrangement, the projection lens holding mechanism may include a plate-shaped lens holding member having a circular opening at the center thereof. Namely, the projection lens holding mechanism may hold the projection lens by inserting the lens-holding barrel into the circular opening with the collar being disposed on the outer circumference of the circular opening.
In the cylindrical lens-holding barrel of the projection lens, the position-adjusting holes, for instance, may be formed on X-axis and Y-axis being orthogonal to each other and also orthogonal to the illuminating optical axis of the optical path formed by the plurality of the lenses housed therein. Specifically, total four position-adjusting holes may be formed, two of position-adjusting holes being formed on the X-axis in an opposing manner and the other two position-adjusting holes being formed on the Y-axis in an opposing manner. More specifically, the position-adjusting holes may be formed on upper, lower, left and right sides of the lens-holding barrel when the lens-holding barrel is seen from the projection side. The orthogonal two axes may not cross the illuminating optical axis.
The position adjuster may adjust the lens position by advancing and retracting the pins inserted into the pair of position-adjusting holes formed on the lens-holding barrel. For instance, the position adjuster may have mutually opposing pins being inserted to a pair of position-adjusting holes and the lens to be adjusted may be held by the tip of the pins, where advancement and retraction of one of the pins causes retraction and advancement of the other pin while the pins are in contact with the outer circumference of the lens. Incidentally, such advancement and retraction of the pins may be conducted by automatic control by a computer and the like or by manual operation by a worker.
Further, in order to detect the image light, the image light projected from the projection lens on the screen may be checked by the naked eye or may be detected by an image pickup device such as a CCD camera provided on the backside of the screen to be image-processed. Incidentally, the image light projected by a projection lens may be directly detected by an image pickup device without projecting the image light on a screen.
The predetermined test pattern may include a pattern in which light-shielding areas are vertically or horizontally arranged in stripes at regular interval. The test pattern may be provided for respective three colors of RGB (Red, Green and Blue).
According to the present invention, the projection lens may be manufactured with the following steps.
(1) Initially, the position-adjusting holes are formed on the cylindrical lens-holding barrel of the projection lens at a position on X-axis and Y-axis being orthogonal to each other and also orthogonal to the illumination optical axis of the optical path formed by the plurality of lenses housed therein. Namely, four position-adjusting holes, i.e. two opposing position-adjusting holes formed on the X-axis and two opposing position-adjusting holes formed on the Y-axis are formed on the lens-holding barrel.
(2) A pre-adjusted projection lens is prepared, where the lens to be adjusted is arranged in a loosely-fitted manner and other lenses are disposed and bonded with reference to the profile thereof in the lens-holding barrel.
(3) The pre-adjusted projection lens is held at the lens-adjusting position by the projection lens holding mechanism (Projection Lens Holding Step). The pins of the lens position adjuster are inserted into the respective position-adjusting holes to hold the outer circumference of the lens to be adjusted by the tips of pins at four points.
(4) In the above-described conditions, an adjustment light beam is irradiated by the light source (Light Beam Irradiation Step), so that the image light including the predetermined test pattern is irradiated onto the pre-adjusted projection lens by the image light irradiation mechanism in accordance with the adjustment light beam (Image Light Irradiation Step) and is projected on a screen etc. in an enlarged manner.
(5) While the projected image on the screen is observed, the position of the lens to be adjusted in X-direction is adjusted by the lens position adjuster on the side of X-axis (Lens Position Adjustment Step). Specifically, tips of a pair of pins inserted into the pair of position-adjusting holes on the X-axis are brought into contact with the outer circumference of the lens, where advancement of one of the pair of pins causes retraction of the other pin and retraction of the one of the pins advances the other. With such an arrangement, the lens position is manually adjusted in X-direction by advancing and retracting the pair of pins. In the same manner, the position of the lens in Y-direction is manually adjusted by the lens position adjuster on the side of Y-axis. Accordingly, the position of the optical axis between the plurality of the lenses can be accurately adjusted.
During the optical axis adjustment work, the lens position is adjusted so as to minimize the flare etc. and sharpen the image of the predetermined test pattern while observing the quality of the projected image.
(6) The lens of which position is adjusted is bonded to the lens-holding barrel by an adhesive (Bonding Step).
(7) Finally, the projection lens is moved from the lens holding position and removed from the projection lens manufacturing apparatus to complete the manufacturing process of the projection lens. By repeating the process, the projection lens can be continuously manufactured.
According to the present invention, since the above-described manufacturing steps are applied to manufacture a projection lens, the position of one of the lenses of the projection lens can be independently adjusted with high accuracy in the X-direction and the Y-direction orthogonal to each other. Therefore, the direction to be adjusted can be easily recognized as compared to a conventional arrangement where the lens is adjusted by pins in three directions. Since only two lens position adjusters corresponding to the respective axes directions are required, the adjustment work of the optical axis position can be facilitated. In the above arrangement, since a pair of position-adjusting holes are respectively provided along the respective axes and the lens position adjusting mechanism are inserted into the pair of the position-adjusting holes to be linearly advanced and retracted, so that it is not necessary to enlarge the size of the opening of the position-adjusting holes as in a conventional arrangement, thereby providing a projection lens capable of preventing light leakage and projecting an appropriate image.
Since the lens position adjuster is provided on the side of the projection lens manufacturing apparatus instead of the side of projection lens, the number of components of the projection lens can be reduced, thereby reducing manufacturing cost, size and weight of the projection lens.
In the manufacturing apparatus according to the present invention, since the lens itself is moved instead of the lens-holding barrel, the optical axes of other lenses fixed to the lens-holding barrel (if present) are not shifted relative to the adjustment light source. Therefore, the axes of the other lenses and the lens to be adjusted can be easily aligned, thereby adjusting the position of the optical axis with high accuracy.
In the manufacturing apparatus according to the present invention, since the position of the lens to be adjusted is adjusted before the lens is bonded to the lens-holding barrel, the lens-holding barrel is not distorted by adjusting the position of the lens. Therefore, since there is no need to provide a distortion absorber on the lens-holding barrel, the size of a lens holding frame and the projection lens can be reduced. Further, since the lens-holding barrel is not distorted, there is no need to heat the lens-holding barrel for removing the distortion. Accordingly, a heat-sensitive material may be used for the lenses, so that the lens material is not limited. Additionally, since the position of the lens is adjusted before being bonded to the lens-holding barrel, the position of the lens can be finely adjusted with ease and with high accuracy.
In the above-described projection lens manufacturing apparatus, the lens position adjuster preferably has: first and a second pins that are respectively inserted into the pair of the position-adjusting holes and abut to the outer circumference of the lens to be adjusted; a biasing portion that biases the first and the second pins toward each other; and an advancement/retraction portion that advances and retracts the first pin relative to the second pin, the advancement and retraction of the first pin causing retraction and advancement of the second pin.
According to the above arrangement, the pins are respectively inserted into the position-adjusting holes facing each other on a predetermined axis, and the pins are biased by the biasing portion toward each other to hold the lens. Then, the advancement/retraction portion is operated to advance and retract the first pin, so that the position of the lens can be adjusted with ease while holding the lens with the two pins. Further, the position of the lens can be adjusted on the other axis in the same manner.
The biasing portion is preferably a cylinder device provided for each of the pin that biases the pins by fluid pressure.
According to the above arrangement, the pins can be always positioned at a regular position by maintaining the pressure of the fluid such as air and oil inside the cylinder device at a constant level. Therefore, when a projection lens is exchanged to manufacture the next projection lens, the lens to be adjusted can be approximately located around a position of the optical axis and only fine adjustment of the deviation of respective projection lens is required, so that the position adjustment work can be facilitated.
The advancement/retraction portion is preferably a micrometer head that advances and retracts the first pin relative to the second pin.
According to the above arrangement, since a micrometer head with high resolution of 1 xcexcm level can be used, the accuracy in adjusting the position of optical axis of the lens can be further enhanced. Incidentally, the micrometer head can be appropriately exchanged to the one with different resolution in accordance with the design of the projection lens to be manufactured.
The projection lens manufacturing apparatus described above preferably includes a drive mechanism that moves the projection lens holding mechanism from a position where the projection lens position adjuster is located to a position where a projection lens to be manufactured is supplied.
According to the above arrangement, since the drive mechanism moves the lens holding mechanism between the position where the projection lens position adjuster is provided and the position where a projection lens to be manufactured is supplied, the adjusting position and the supplying position of the projection lens are separated, so that the projection lens can be easily set at a position without interfering with other mechanisms.
The drive mechanism preferably includes a rotary drive mechanism that rotates the lens holding mechanism around a base end of an arm connected to the lens holding mechanism on a plane orthogonal to the illuminating optical axis and moves the lens holding mechanism between a position on the illumination optical axis and a position off the illuminating optical axis.
Since the lens holding mechanism turns around the base end of the arm between the position on and off the illuminating optical axes, when the projection lens is set at a position off the illuminating optical axis, the projection lens can be easily set on the position without interfering with other mechanisms, thereby efficiently manufacturing the projection lens.
In the projection lens manufacturing apparatus described above, an adhesive injection hole for injecting an adhesive for bonding the lens of which position has been adjusted is preferably formed on the lens-holding barrel, and the bonding mechanism preferably includes a light beam irradiator that cures a photo-curing adhesive injected into the adhesive injection hole.
The adhesive may be manually injected into the adhesive injection hole or may be automatically injected by providing an adhesive-injecting portion for injecting the photo-curing adhesive into the adhesive injecting hole to the bonding mechanism of the projection lens manufacturing apparatus.
The bonding mechanism may include an inserting portion inserted into the adhesive injecting hole formed on the projection lens such as an adhesive-injecting tube for injecting ultraviolet-curing adhesive, where an adhesive is injected from the adhesive-injecting portion through which a light beam, such as ultraviolet is irradiated from the light beam irradiating portion. The pins and the adhesive-injecting tube may be disposed in parallel and may be integrated. The position of the adhesive-injecting holes may be rearranged in accordance with the integral arrangement described above.
According to the above-described arrangement, the lens can be bonded to the lens-holding barrel by irradiating the light beam from the light beam irradiating portion after injecting the photo-curing adhesive from the adhesive-injecting portion through the adhesive-injecting hole after the lens position is adjusted by the lens position adjuster. Since the lens is bonded with the lens position being fixed, production failure caused during the bonding process can be minimized.
The projection lens manufacturing apparatus described above may preferably include a light-shielding mechanism provided on the optical path between the light source and the projection lens, the light-shielding mechanism blocking the light beam irradiated by the light source from being introduced into the projection lens.
The light-shielding mechanism may be a plate-shaped member and the like for shielding the light from the light source provided on the optical path between the light source and projection lens.
According to the above arrangement, when the photo-curing adhesive is cured by irradiating a light beam by the light beam irradiating portion, the photo-curing adhesive is not erroneously cured by mixing the light beam irradiated by the light source.
In the projection lens manufacturing apparatus described above, a screen on which the image light is projected through the projection lens is preferably located on the downstream of the optical path of the projection lens.
According to the above arrangement, since the position of the projection lens can be adjusted while observing the image projected on the screen in an enlarged manner, the position of the optical axis can be accurately adjusted.
In the projection lens manufacturing apparatus described above, the optical path from the light source to the projection lens is preferably arranged approximately along a vertical direction.
According to the above arrangement, since the optical path is arranged along the vertical direction, the plurality of lenses of the projection lens are horizontally laid, so that the adjusting direction of the lens to be adjusted becomes horizontal. Even when the injecting portion (e.g. the adhesive-injecting tube for injecting ultraviolet-curing adhesive) is horizontally laid relative to the pin, the adhesive remaining on the tip of the inserting portion flows in vertical direction, so that the adhesive is not adhered on the tip of pins, thereby efficiently manufacturing the projection lens.
In the projection lens manufacturing apparatus described above, a reflection member that reflects to bend the optical path of the image light irradiated by the projection lens and a screen on which the reflected image light is projected are preferably provided on the downstream of the optical path of the projection lens.
For instance, the reflection member may reflect the image light irradiated by the projection lens approximately at right angle.
When the image light irradiated by the projection lens is reflected by the reflection member at right angle to be projected on the screen, the optical path direction of the manufacturing apparatus body is arranged parallel to the screen surface. Therefore, the manufacturing apparatus body other than the screen can be downsized as compared to an arrangement in which the optical path from the manufacturing apparatus body to the screen is linearly arranged in vertical direction.
A projection lens manufacturing method according to another aspect of the present invention is for manufacturing a projection lens including a lens-holding barrel in which an optical path is set, a plurality of lenses sequentially disposed on an illuminating optical axis of the optical path, and a pair of position-adjusting holes formed on the lens-holding barrel, the position-adjusting holes being used for adjusting the position of at least one of the plurality of the lenses in a direction along mutually orthogonal two axes on a plane orthogonal to the illuminating optical axis, the method including the steps of: holding the projection lens to be adjusted at a lens adjusting position for adjusting the position of the lens to be adjusted on the illuminating optical axis; irradiating an adjustment light beam by a light source; generating an image light including a predetermined test pattern in accordance with the light beam irradiated by the light source and introducing the image light into the projection lens located on the illuminating optical axis; adjusting the positions of the respective lenses to be adjusted along the two axes through the position adjusting hole while detecting the image light irradiated by the projection lens into which the image light is introduced; and bonding the lens with the position thereof being adjusted on the lens holding barrel.
According to the above aspect of the present invention, since the projection lens can be manufactured in the same manner as described above, approximately the same advantages as the projection lens manufacturing apparatus of the projection lens can be obtained, and the present invention can be achieved. In other words, one of the lenses of the projection lens can be independently adjusted along the two mutually orthogonal axes with high accuracy. Therefore, the direction to be adjusted can be easily recognized as compared to a related art arrangement, thereby facilitating the adjustment work. Further, since the pins for adjusting the position of the lens are provided on the manufacturing apparatus instead of the side of the projection lens, the number of the components of the projection lens can be reduced, thereby reducing manufacturing cost, size and weight of the projection lens.
In the projection lens manufacturing method, since the lens itself is moved instead of the lens-holding barrel, the optical axes of other lenses fixed to the lens-holding barrel (if present) are not shifted relative to the adjustment light source. Therefore, the axes of other lenses and the lens to be adjusted can be easily aligned, thereby adjusting the position of the optical axis of the lens with high accuracy.
Since the lens to be adjusted is bonded to the lens-holding barrel body after the position thereof being adjusted, the lens-holding barrel is not distorted by adjusting the position of the lens. Therefore, since there is no need to provide a distortion absorber on the lens-holding barrel, the size of the lens holding frame and the projection lens can be reduced. Further, since the lens-holding barrel is not distorted, there is no need to heat the lens-holding barrel for removing distortion. Accordingly, a heat-sensitive material can be used for the lens, so that the lens material is not limited. Additionally, since the position of the lens is adjusted before being bonded to the lens-holding barrel, the position of the lens can be finely adjusted with ease and with high accuracy.
A projection lens according to still another aspect of the present invention is manufactured by the above projection lens manufacturing method. According to the above aspect of the present invention, approximately the same advantages as the manufacturing apparatus and the method of projection lens can be obtained, so that a projection lens capable of adjusting the position of the optical path with high accuracy, projecting the image with high quality and reducing the manufacturing cost can be provided.
A projector according to further aspect of the present invention includes the above projection lens. According to the above aspect of the present invention, approximately the same advantages as the projection lens can be obtained, where the manufacturing cost can be reduced and a high-quality image can be projected.